Electric-furnace regulator.



R. H. WHITE.

ELECTRIC FURNACE REGULATOR.

APPLICATION FILED SEPT. s. 1914.

1,149,238. Patented Aug. 10, 1915. I

7 "Yb (P 7750 46 5 UETTEI) sT TEs PATENT OFEIOE AY HILL WHITE, or NIAGARA FALLS, NEW YORK, Asszenon To NORTON COMPANY, or WORCESTER, MASSACHUSETTS, A CORPORATION OF MASSACHUSETTS.

ELECTRIC-FURNACE REGULATOR.

To all whom it may concern:

Be it known that I, RAY HILL WHITE, acitizen of the United States, residing at Niagara Falls, in the county of Niagara and State of New York, have invented certain new and useful Improvements in Electric- Furnace Regulators, of which the following is a specification.

My invention relates to an automatic regulating device for electric furnaces, and has for its object to obviate certain difiiculties liable to arise when the regulation is effected by movement of an electrode or electrodes controlled by an automatic regulating device.

On account of the Weight and inertia of the system to be moved, which includes not only a ponderous electrode but its electrical connections, there is a tendency for the electrode to over-travel particularly when lowered, beyond the point of proper regulation. When this occurs, the automatic regulator must then reverse the movement of the electrode, with a resulting uneven regulation which causes trouble at the power station and is detrimental to the furnace operation.

By my invention, upon the occurrence of such a change of furnace conditions as to require a change of position, such as the lowering ofv an electrode, the electrode 'is moved to a' point-short of that required, is then stopped and if the resulting position of the electrode is not that required by the then existing conditions, is again lowered and stopped, until the normal position is reached.

'The electrode or electrodes are thus moved.

by a series of impulses always in the same direction until the required position is reached. I

One particular form. of switching apparatus, embodying the invention is described in this specification and the accompanying. drawings, in which'the system is diagram-. matically shown.

Referring to the drawings, 1 is an electric furnace with a stationary electrode 2and a movable electrode 3 to which. is attached the flexible electrical conductor 4;

On the top of the electrode holder 5 is fastened a cable properly insulated from the electrode. The other end of the cable is at- 'tached to a drum 7 which is driven through suitable gearing 8 by the -reversing motor 9, which may be a two-phase three-w re mo Specification of Letters ratent. Patented Aug. 10, 1915.

. Application filed September 8, 1914. Serial No. 860,768.

tor, supplied with current from any suitable source.

Surrounding the bus bar of the movable These bridges have portions arranged to extend downward into a series of mercury cups 15', 15", 16, 16', 17', 17", 18, 18", 20', 20", 22, 22. To one side of the center of the beam 12 is attached the plunger or armature 13 of a solenoid l1, tending when energized to raise the right-hand portion of the beam. When the current on the furnace is at the point desired this beam is balanced in a horizontal or neutral position, by adjusting the movable weight It to a position in which the upward pull of the solenoid 11 will be counteracted. When the right-hand portion of the-beam falls, which movement would be caused by the weakening of the magnet corresponding to a low current on the furnace, the motor circuit is closed, the gaps between 15'-15" and 16-16 being bridged, and the motor is started in a direction which unwinds the cable on the Simldrum, thus lowering the electrode. larly, when the left-hand portion of the beam falls, as when there is a too large current on. the furnace, gaps 17 -17 and 18--18 are bridged and the motor is start ed in the reverse direction, thus raising the electrode.

In order to prevent the overtravel of the electrode, I provide a connection at the point 19 to the solenoil coil and a second connection at the point 21, whereby a smaller or larger number of turns of the solenoid may be included in one or the other of the circuits to be later described. When the beam is in. a horizontal position, the circuit is from the transformer 10, through wire 30, and 31' to mercury cups 20, 20", wire 32,

to point 19, the coils of the solenoid above that point, thence through wire 33, back to the transformer. In this position the upward pull of the solenoid is suflicient to counteract the weight 14. If for any reason, thecurrent in the circuit ust described weakens, the weight 14 preponderates and the right-hand side of the beam sinks, closing the circuit first through mercury cups 522, 22", and then breaking the circuit through mercury cups 20,20,the terminals of the bridges being of such length that the circuit is always closed by 01.; bridge or the other. The circuit will then be from the transformer, through wires 30, 31, cups 22', 22" to point 21, and thence back to the transformer 10, all the coils of the solenoid being included in the circuit. The additional number of turns thus included in the solenoid is so proportioned as to produce an upward pull suflicient to bring the beam to a horizontal position at a current strength somewhat less than that for which the switch is normally set.

The operation of the device will best be understood from a specific example :'l hus if the normal working current in the furmice is to be 4,000 amperes, the weight 14 on the switch beam is adjusted to maintain the horizontal position of the beam, when the current on tliefurnace is shown by measurement to be 000 amperes. In this position, the series transformer delivers current,which is in quantity a definite proportion of 4,000 amperes, e. g., 4 amperes, through the bridge across mercury cups 20, 20", to those coils of the solenoid above the point 19, the upward pull of the solenoid balancing the downward push of the weight. If now, the current in the furnace drops to 3,000 amperes, the transformer is only delivering 3 amperes, the pull of the solenoid is weakened, the right-hand end of the switch-beam drops and current now flows from the transformer through wire 30, to point 35, wire 34, cups 22", 22', to point'21, and thence through all the coils of the solenoid backto the transformer; The rising of the left-hand side of the switch-beam has, in the meantime, broken the circuit between cups 20, 20. The motorconnections having been closed at cups 15, 15 and cups 10, 10", the motor isoperated to lower the electrode, thereby diminishing the resistance, and causing an increased current flow. The number of additional turns in the solenoid is such that as soon as the current strength reaches 3800 amperes, the solenoid will be sufficiently energized to bring the beam again to a horizontal or neutral posit'ion; the motor-circuits are therefore opened, and the motor stops. The inclusion of the additional turns of the solenoid between points 19 and 21, therefore acts automatically to re-set the point of switch-beam adjustment at 3800, instead of at 4,000. The momentum of the lowering electrode has however probably caused it to continue its downward movement, even though the motor has Stopped, to a point at which say 3900 amperes are being used in the furnace.

But the beam having been restored to its horizontal or 4,000 am ere position, and the current in the furnace )eing still below that amount, the right-hand portion of. the beam again sinks, the motor is again started and the additional solenoid coils again out in. The again strengthened solenoid forthwith restores the switch-beam to the horizontal position, a slight lowering of the electrode having been effected. If this further descent is not sufiicient to bring the current up to the desired point, the action is repeated until the current is at the point required.

Should the current in the furnace rise above the predetermined point, the lefthand side of'theswitch-beam sinks and the motor circuits are closed through cups 17, 17", 18, 18', to operate the motor in the reverse direction to raise the electrode, until normal conditions are restored. The mass oi the upwardly moving'system acting against the motor 1s sufiicient to prevent overtravel when the motor is stopped.

While I have described the switch as a current regulator and operated by variations in current strength, it may obviously be operated by variations in potential, or by variations in power. Thus in case the furnace has two movable electrodes, two regulators may be used, each so connected that the potentials between the electrodes and the bath (and consequently the length of the arcs) are maintained equal. In this case, the current for the switch solenoids is supplied from leads running from a neutral point of the furnace, such as the bottom, or from a third electrode introduced for this purpose, to the cables connected to the electrodes.

In cases where regulation in accordance with power consumed is desired, there may be substituted for the single solenoid, a double coil, one of which is a potential coil, in such manner that the strength of the magnet varies with the power or watts. The well-known Kelvin balance principle is, in this case, applicable, any anti-hunting levice being connected to one of the current coils, which operates the switchbeam.

It is equally obvious that instead of operating the switch-beam directly, it may be operated through a. relay, which in turn is operated by any of the well-known current, potential or power-indicating instruments, and that instead of a pivoted switch beam, I may use any other type of switch suitable for-the purpose indicated, as for example, a switch with sliding contacts may be mounted to be moved vertically or horizontally or in other positions by the solenoid.

Moreover, my invention while particularly applicable to electric furnaces, is applicable in any case where the desired regulation between moving members is rendered diflicult because of hunting or overtravel caused by the mass or inertia of the system; and, further, may be used not only for lowering such masses, but for controlling movement in either of two directions, as, for example, in the case of horizontal movements.

It will further be evident that instead of an electric motor for raising and lowering the electrode, I may use a mechanical motor,

provided with starting, stopping and reversing mechanism, operated from or controlled by the automatic switch mechanism described.

1. The combination ofa movable electrode, a motor for moving the electrode, a

motor-controlling switch having a circuitclosing member, counterbalancingmea'ns to maintain said member in neutral position comprising a solenoid in circuit with a current source responsive to variations in position ofthe electrode, and means controlled by the circuit-closing member for varying the number of-- solenoid turns to counterbalance the circuit-closing member at a predetermined current strength and also at a cuit-closing member for varying the number of solenoid turns to counterbalance the circuit-closing member at a predeterminedcurrent strength and also at a less current strength.

3. The combination of a movable electrode, a motor for moving the electrode, a motor-controlling switch having a circuitclosmg member, means. for maintaining said member in neutral position comprising a solenoid, a current source in circuit with said solenoid, responsive to variations in position of the electrode, the' solenoid hav- 111g two sets of turns, eachsufficient'to maintam the circuit-closing member in neutral position, one set, normally in circuit, so actlng at a predetermined current strength and the other set so acting at a less current strength and means controlled by the circuit-closing member for opening and closing the circuits of said sets of coils,

4. The. combination of an electric motor, a motor-controlling switch having a movable circuit-controlling member, a solenoid having its plunger connected to said member, the solenoid having two sets of coils, each set proportioned to maintain, at difi'erent current strengths, the member in a predetermined position.

5. The combination of an electric motor, a motor-controlling switch comprising a movable member, switches for the motor circuits controlled by said member and normally open when the member is in neutral position, a solenoid having its plunger connected to the member, the solenoid having two sets of coils of difl'erent numbers of turns, but of equal efiect at definite but different current strengths, separate circuits for each coil energized by a current source of varying power, and switch devices controlled by the member for controlling said circuits.

6. The combination with an electric motor of a motor-controlling switch comprising a movable member, a variable source of power, a solenoid coil, in circuit with said power source, having its plunger connected to the member, whereby said member is maintained in neutral position at a definite current strength, a switch for said circuit on the member, and closed in the neutral position of the member, a second coil in series with the solenoid coil and in a supplemental circuit with the source of power, whereby the solenoid is of equal eiiect at a less amount of current, and a normally open switch for the supplemental circuit carried by the member.

7 In combination with an electric motor, a motor-controlling switch comprising a pivoted beam, a weight on said beamat one side of said pivot, a solenoid having its plunger connected to the beam on the same side as the weight, the solenoid provided with coils to produce an equal weightcounterbalancing effect at two different definite current strengths, and separate means carried by the beam for connecting the solenoid coils alternately in either relation.

In testimony whereof I afiix my signature 

